火控系统故障诊断与性能检测设备研究

从设备主要功能、设备硬件设计、检测软件及故障诊断软件设计等方面,系统地分析了检测设备的总体设计方案,功能特点,信号采集、处理与控制等。设计过程突出了理论与实践相结合的设计理念,针对某型火控系统的特点,结合实际研制过程,该方法具有较好的应用推广价值。     

超音速环形引射器空气引射启动特性试验

建立了超音速环形引射系统,对环形引射器空气引射启动特性进行了试验研究.试验结果表明:管道马赫数越大,则系统启动压强越高,同时盲腔真空度越高;混合室收缩比越小,系统启动压强越低;若管道马赫数较大,而第二喉部长径比和亚音速扩压段面积比过小,引射器启动过程可能不稳定,甚至无法启动;混合室收缩比、环型引射器扩压管道参数对盲腔压强无影响.     

Factors that affect the optimal amount of central control in complex systems

Whereas much of the previous research in complex systems has focused on emergent properties resulting from self‐organization of the individual agents that make up the system, this article studies one vital role of central organization. In particular, four factors are conjectured to be key in determining the optimal amount of central control. To validate this hypothesis, these factors are represented as controllable parameters in a mathematical model. For different combinations of parameter values, the optimal amount of central control is found, either analytically or by computer simulation. The model is shown to provide results that match well with the level of control found across a broad spectrum of specific complex systems. This model also provides general guidelines as to how combinations of these factors affect the desirable level of control and specific guidelines for selecting and evaluating leaders. These results indicate that all of these factors, though not exhaustive, should be considered carefully when attempting to determine the amount of control that is best for a system. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

一种无缓冲的光互连网络的吞吐率性能分析及优化

针对当前高性能计算机光互连网络中存在的光缓冲不易实现的问题,提出了一种无缓冲的光互连网络结构BOIN,并在对网络结构进行建模和分析的基础上,研究了网络的吞吐率随不同的输入负载和网络规模而变化的规律,给出了在一定的互连总规模和输入负载下,网络实际吞吐率达到最大值时网络拓扑结构所必须满足的条件.最后用模拟实验证明了这一结果的正确性.     

小子样条件下航天轴承性能可靠性建模与评估

航天油润滑轴承可靠性具有小子样、无失效数据特点,即使采用性能可靠性方法进行建模与分析,仍存在性能数据不足问题。提出小子样条件下航天轴承性能可靠性分析的多层贝叶斯模型及模型求解方法。通过失效分析,建立轴承性能退化过程模型。利用自助法、试验数据、物理模型和专家经验等确定Bayes验前分布,并采用MCMC方法解决Bayes计算问题。实例分析表明,该方法具有较好的适用性,是解决小子样条件下长寿命产品可靠性建模与评估问题的一种有效途径。     

Linux虚拟文件系统层的路径检索加速

为解决 Linux 内核传统路径检索日益凸显的开销问题,提出Staged Lookup以加速路径检索,通过动态缓存热目录来减少文件访问的时延。Staged Lookup的核心在于缓存频繁使用的目录项,从而避免从根节点重复遍历路径。不同于从根结点开始的检索操作, Staged Lookup扩展了搜索策略,允许从最近缓存的目录项向后或向前进行路径检索。在Linux内核版本3.14和5.4上部署Staged Lookup的原型,并开展实际系统测试。实验数据显示,相比于传统的路径检索方式,Staged Lookup能实现高达46.9%的性能提升。     

灰色层次模型战术数据链综合性能评估方法

从战术数据链的功能模型出发,考虑影响战术数据链正常功能发挥的各方面因素,基于灰色层次理论,构建了战术数据链综合性能评估指标体系,在此基础上提出了战术数据链综合性能的灰色层次模型。应用实例的过程及结果表明,评估方法简易可行,评估结论相对真实合理,对战术数据链性能评价及新功能的开发具有理论指导意义和应用价值。     

Kinetics in counterinsurgency: some influences on soldier combat performance in the 1st Australian Task Force in the Vietnam War

Counterinsurgency is often characterized by large numbers of small fire-fights interspersed with a few larger battles. Heavy firepower contributes to the outcome of the larger battles but the smaller contacts are often fought by infantry without heavy weapons support. Infantry combat performance in these fire-fights is therefore a key concern. It has been fashionable to discuss soldier combat performance in terms of ‘firers’, ‘non-firers’, and ‘posturers’, but we argue that other factors have a greater impact. We provide a detailed statistical analysis of a selection of combat factors, using combat data collected by the 1st Australian Task Force (1ATF) during the Vietnam War. An accepted measure of soldier lethality is the ‘shots per casualty’ ratio. Using this measure we are now able to describe the combat performance of the Australian infantry section in Vietnam in much greater detail than has hitherto been possible.     

SpaceFibre星载数据网络低延时确定性调度算法

针对超高速SpaceFibre星载网络中多源数据传输的确定性和实时性应用需求,提出一种分类细粒度低延时确定性调度算法。该算法基于差异化调度策略的思想,将数据流划分为三类。为实现网络资源的细粒度分配,引入扩展时隙。该算法采用无冲突均匀调度方法,降低了数据包的平均排队延时。为适应有效载荷组网的航天应用场景,该算法兼顾网络拓扑结构生成调度方案。为验证算法有效性,在OPNET仿真平台下利用自定义建模技术搭建网络仿真模型。仿真结果表明:相比优先权调度和无冲突连续调度机制,该算法实现了时间敏感数据流的确定性传输;随着时隙数目的增加,网络的延时性能和抗抖动性能显著提升,吞吐量性能得到保证;该算法具有一定的航天工程实用价值。     

并行程序中同步瓶颈的检测和优化方法

针对并发程序中锁的不当使用可能导致性能瓶颈的问题,提出检测和优化并发程序中同步瓶颈的方法IdeSync。IdeSync使用静态分析方法获取同步方法和同步块,构建静态同步依赖图,采用基于执行路径的动态分析技术进行同步依赖关系分析,构建同步依赖图。为了暴露性能瓶颈,在同步依赖图上通过增加程序工作负载的方式,监测临界区的性能变化,并针对检测到的同步瓶颈给出优化建议。在实验中通过HSQLDB、SPECjbb2005和RxJava等12个大型实际应用程序对IdeSync的有效性进行验证,共检测到72个同步瓶颈,根据优化建议进行优化后程序性能均有所提升。实验表明,IdeSync能够有效地检测和优化同步瓶颈。